greenscreen

Short definition from Wiktionary

Noun

1. 1
   The alternate version of bluescreen, having the background green instead of blue.
2. 2
   The display of an IBM 3270 or similar monochrome monitor.

Verb

1. 1
   To film a subject in front of a greenscreen.
2. 2
   To remove the background from a video and replace it with a different image or scene; to composite.